Retinal malfunction, due to degenerative retinal diseases, is a leading cause of blindness and visual impairment. Implantation of a retinal prosthesis is a technology for restoring some useful vision in individuals suffering from retinal-related blindness.
The retina is a multi-layered light-sensitive structure that lines the posterior, inner part of the eye. The retina contains photoreceptor cells, for example rods and cones, which capture light and convert light signals into neural signals transmitted through the optic nerve to the brain. A bipolar cell layer exists between the photoreceptors and ganglion cells of the retina. The bipolar cell layer transmits signals from the photoreceptors to the ganglion cells whose axons form the optic nerve and transmit visual information to the brain.
Grill W., et al. describe in an article, entitled “Implanted Neural Interfaces: Biochallenges and Engineered Solutions,” Annu. Rev. Biomed. Eng. 2009. 11:1-24, a regenerative sieve electrode that has holes to allow processes from a severed neuron to grow through. The article includes a schematic illustration of a sieve electrode.
U.S. Pat. No. 6,908,470 to Stieglitz describes a sieve electrode for connection to a nerve stump, which is composed of a thin flexible substrate with a plurality of ports for nerve filaments and several electrodes that are disposed on at least some of said ports on said substrate and adapted for being electrically contacted via conductors on said substrate, as well as of at least one counter-electrode. The substrate presents tabs protruding from the edge for fixing the substrate on a face of the nerve stump, which serve, at the same time, as carrier of the counter electrode. With this sieve electrode a neuro-technological interface is provided that is described as permitting a low-lesion contact with the nerve stump at a maximum of useable surface for the ports.
U.S. Pat. No. 4,969,468 to Byers describes an electrode array device for making multiple electrical contacts with cellular tissue or organs. The electrode array includes a base, a two dimensional array of conducting protuberances arising from the base and serving as electrodes, and conductors embedded onto the base and connected to such protuberances for transmitting electrical signals to and/or from the protuberances. The protuberances may also include an insulating layer which covers either the entire protuberance or which leaves the tips exposed for making focused electrical contact. Electrode arrays may be used singly or in combination with a second electrode array so as to form a sandwich around a target tissue. The sandwich electrode array may employ indexing cones for aligning the opposing electrode arrays and for limiting their vertical proximity. The conductors of the electrode array may be electronically connected or coupled to processing circuitry which amplifies and analyzes the signal received from the tissue and/or which generates signals which are sent to the target tissue and possibly coordinates the generated signals with signals which originate with the tissue.
The following patents and patent application publications may be of interest:
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The following articles, which are incorporated herein by reference, may be of interest:
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Seo J M., et al., “Biocompatibility of polyimide microelectrode array for retinal stimulation,” Materials Science and Engineering: C, Volume 24, Number 1, 5 Jan. 2004, pp. 185-189(5)”
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Wallman L., et al., “The geometric design of micromachined silicon sieve electrodes influences functional nerve regeneration,” Biomaterials 2001 May:22(10):1187-93
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